1. Field of the Invention
The present invention relates to an attaching method for attaching a supporting plate to a substrate and to finely adjust the alignment of the support plate and a semiconductor wafer when attached.
2. Description of the Background Art
There is a continuing need to make IC cards and cell phones thinner, smaller, and lighter. In order to satisfy this need, semiconductor chips to be incorporated therein must be thin. Although at present the thickness of a wafer which forms a semiconductor chip is 125-150 μm, it is expected that the thickness of a semiconductor wafer must be 25-50 μm for a next generation of chips.
A surface of a semiconductor wafer on which a circuit device has been formed needs to be supported by a tape or a sheet member in the process of thinning the semiconductor wafer with a grinder. Document 1 has disclosed an apparatus for attaching a supporting plate to a semiconductor wafer.
The apparatus of Document 1 comprises a pair of hot plates provided in the upper portion and the lower portion, and a pair of vacuum pots provided outside the hot plates, so that a layered structure of a semiconductor wafer and a supporting plate can be formed by pressing in a pressure-reduced atmosphere. Especially, according to Document 1, an air plunger which also functions as a damper is used as a means for elevating and lowering the upper hot plate instead of a hydraulic press, so that a semiconductor wafer is prevented from being damaged by adverse pressure generated when the layered structure expands due to the heat of the hot plate.
[Document 1] Japanese Patent Application Publication No. 2002-192394
Document 1 uses a semiconductor wafer whose diameter is 150 mm, and a supporting plate whose diameter is 150.5 mm. More specifically, a positioning plate in which a hole having a diameter of 160 mm is formed in the center is prepared, and a semiconductor wafer and a supporting plate are inserted into the hole of the positioning plate and attached to each other (paragraph 0024-0028).
As described above, if the diameters of the semiconductor wafer and the supporting plate are almost the same, the layered structure can be handled as the semiconductor wafer alone when it is transferred. However, this technique has a drawback in that displacement occurs because the semiconductor wafer and the supporting plate whose diameters are about 150 mm are inserted into the hole whose diameter is 160 mm.
Also, this technique uses an epoxy resin or the like as an adhesive for attaching a supporting plate to a semiconductor wafer. Since the rigidity of an epoxy resin decreases with heating, displacement easily occurs after positioning is performed.
In order to solve the above-mentioned problems, an object of the present invention is to provide an attaching device and an attaching apparatus for a supporting plate, and an attaching method for a supporting plate which make it possible to reliably align a substrate with a supporting plate when the diameters thereof are the same, and easily correct the alignment even after the supporting plate is attached to the substrate.